Hot-air furnace.



J. ZELLWEGBR. HOT AIR FURNACE.

APPLIGATION FILED JAN.8, 1913.

Patented Apr.'14, 1914.

/NVEIVTOR:

JOHN ZELLWEGER, OF ST. LOUIS, MISSOURI.

HOT-AIR FURNACE.

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To all whom it may concern:

Be it known that I, JOHN ZELLwncnR, a citizen of the United States, residing at St. Louis, Missouri, have invented a certain new and useful Improvement in Hot-Air Furnaces, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to hot air furnaces.

One object of my invention is to provide a hot-air furnace that has a much greater air-heating area than the furnace of corresponding external dimensions of the type heretofore in general use, and which is so designed that the flames from the fuel are fully developed before their heat is utilized.

Another object is to provide a hot-air furnace comprising an air-heating portion and a detached furnace or combustion chamber that is separate and distinct from the airheating portion, said separate parts being so designed and arranged that each can eX- pand and contract independently of the other.

Another object is to provide an air-heating furnace in which the grate of the furnace proper is very wide but shallow so that the bed of fuel on the entire grate and the outlet ports for the fire gases are always within easy reach and View of the fireman, the furnace also comprising an air-heating portion or air-heater which is made up of a plurality of hollow air-heating members of simple design and construction that are arranged behind the combustion chamber in such a manner that they form fire-flues which extend in the direction of travel that the products of combustion would naturally take in flowing out of the combustion chamber.

Other objects and desirable features of my invention will be hereinafter pointed out.

Briefly described, my improved furnace consists of a detached furnace or furnace proper that comprises a combustion chamber, a grate, and an ashpit. and an air-heater separate and distinct from the furnace proper and made up of a plurality of hollow members spaced away from each other and arranged in such a manner that they form a plurality of fire-fines which communicate at one end with the combustion chamber of the furnace and at the other end with a chimney or draft-creating means. The furnace proper is preferably construct- Specification of Letters Patent.

Application filed January 3, 1913.

Patented Apr. 14, 1914. Serial No. 739,951.

ed of brick or other suitable refractory material and is provided with comparatively thick walls so as to conserve the heat and maintain a high temperature inside of the combustion chamber, thereby promoting complete combustion of the fuel. The hollow members that constitute the air-heating portion or air-heater of the furnace are preferably formed of metal and are so designed that there is no possibility of the fire-gases which travel through the fire-flues between said members from entering the air-passageways in which the air circulates and is being heated.

Figure 1 of the drawings is a transverse sectional view of the furnace taken on the line l1 of Fig. 2 looking in the direction indicated by the arrow; Fig. 2 is a longitudinal sectional view taken on the line 22 of Fig. 6; Fig. 3 is a transverse sectional view taken on the line 33 of Fig. 2; Fig. 4: is a longitudinal sectional View taken on the line l-4.- of Fig. 6; Fig. 5 is a horizontal sectional view taken on the line 55 of Fig. 2; Fig. 6 is a horizontal sectional view taken on the line 66 of Fig. 2; Fig. 7 is a detail sectional view illustrating the way in which the air-heating members are connected together; Fig. 8 is a vertical sectional view illustrating a round furnace constructed in accordance with my invention; and Fig. 9 is a horizontal sectional View taken on the line 9-9 of Fig. 8.

Referring to Figs. 1 to 7, inclusive, of the drawings which illustrate the preferred form of my invention, 1 designates the com bustion chamber of the furnace, 2 designates the grate, preferably a shaking grate, 3 designates the ashpit, and at designates a chimney-flue that leads to a stack or chimney 5. The parts just described form the furnace proper of the apparatus and may be of any preferred construction; but I prefer to form the side walls of said combustion chamber from brick or some other suitable refractory material so as to conserve the heat and maintain a high temperature inside of the combustion chamber, thereby promoting complete combustion of the fuel. I prefer to build the grate 2 in sections, as shown in Fig. 6, and provide a fire-door-opening 6 for each section of the grate so that only part of the furnace may be used at one time if so desired. In the furnace herein shown the chimney-fiue 4 is arranged under the ashpit, as shown in Figs. 2 and 4, but this is not essential to the successful operation of my furnace and therefore I do not wish it to be understood that my invention is limited to a furnace in which the chimney-flue extends transversely of the furnace under the ashpit.

The furnace comprises an air-heater which preferably consists of a plurality of hollow air-heating members through which air circulates and a plurality of fire-fines arranged in such a manner that the products of combustion traveling through same will maintain said hollow air-heating members at a high temperature and thus operate to heat the air that circulates through said hollow members, said fire-flues communicating at one end with the combustion chamber and at the other end with the chimney-flue previously mentioned. In the preferred form of my invention, as shown in Figs. 1 to 7 the hollow air-heating members that form part of the air-heater of the furnace consist of substantially oblong-shaped hollow members or boxes A that are arranged in a vertical position behind the transversely extending wall 7 which separates the air-heater from the furnace proper, or, in other words, from the combustion chamber, ashpit and chimney-flue 4t. Said boxes or hollow members A are comparatively narrow but they are high and also deep so as to form long narrow ducts through which the air to be heated circulates. The boxes or hollow members A are spaced apart, as shown in Figs. 5 and 6, and they are arranged at approximately right angles to the rear wall 7 of the furnaceproper so as to form a plurality of vertically disposed fire-flues 8 which communicate at their upper ends with the combustion chamber 1, preferably through means of fire-ports 9 formed in the rear wall 7 of the combustion chamber, and communicate at their lower ends with smokeports 10 that lead into the chimney-flue A, as shown in Fig. 2. Each of the air-heating members A is provided adjacent to its lower end with an air inlet port 11 and adjacent its upper end with an air-outlet port 12, as shown in Fig. 4:, cold air being supplied to the air-heating members A from a cold-airsuppl chamber 13 that extends transversely of tie furnace across all of the air-heating members A, and which is provided with an opening for admitting the air to same, as shown in Fig. 5. The air that is heated in the members A escapes through the air-outlet ports 12 in said members into a hot air collecting chamber 14 which also extends transversely of the furnace across all of the members A, as shown in Figs. 2 and 4, and a supply conduit 15 leads from the hot air collecting chamber 1% to the hot air distributing pipes of the system, not shown, or, if desired, the distributing pipes lead directly to the collecting chamber 14. If desired, dampers 16 may be provided for regudampers, as shown in Figs. 2, 4 and 5, each of which cooperates wit-h a certain number of air-heating members A, thus enabling only a portion of the furnace tobe utilized at one time. 7

The air-heating members A may be formed in various ways but I prefer to construct each of said members from a pair of parallel plates (4 which are connected in any suitable manner to pieces of channel-iron Z) that are arranged between said plates adjacent the marginal edges of same so as to form a narrow oblong-shaped box. The channel Z) at the rear edge of the box terminates some distance from the top and bottom channels of the box, as shown in Fig. 4, so as to form the air-inlet port 11 and airoutlet port 12 in the box, but the other channels at the front and top and bottom edges of the box extend the full height and depth of the box, respectively, so as to prevent the fire gases which travel through the fines 8 from entering the boxor the air which circulates through the box from escaping into the fire-fines. Each of the boxes or airheating members A is provided with one or more tubular-shaped spacing devices 0 that lie between the two side wall plates a of the box and thus hold the intermediate portions of said plates spaced apart, and said side wall plates a are prevented from bulging outwardly by means of one or more hollow stay-bolts or other suitable tubular-shaped members (Z arranged inside of the spacing sleeves 0 and having their ends flared or flanged over, as shown in Fig. 7, so as to bind the side wall plates and spacing sleeves together. The boxes A are held spaced away from each other by means of tubular-shaped thimbles l'T'arranged between said boxes, as shown in Fig. 7, and tie-rods 18 extend transversely through the thimbles 17 and through the hollow stay-bolts (Z so as to se ourely tie all of the boxes or air-heating members together.

lVhile I prefer to construct the members A in the manner above-described I do not wish it to be understood that my invention is limited to such a construction or to narrow oblong-shaped air-heating members for the members in which the air is heated could be formed in various ways without departing from the spirit of my invention. As previously stated, the air-boxes A are arranged at right angles to the front of the furnace proper and the front edges of said' air-boxes bear against the rear side of the transversely extending wall 7 of the furnace and are held against said wall by tie- .rods or in any other suitable manner. Vertically disposed members 19, preferably pieces of channel-iron, are arranged between the air boxes A adjacent the rear and top edges of said boxes, as shown in Fig. 6, so as to form the rear and top walls of the fire-fines 8. The front and bottom walls of the fire-fines are formed by the transversely extending wall 7 and by the foundation, respectively. If desired, each of the boxes or hollow members A may be provided with an auxiliary heating plate 20 arranged inside of same, as shown in Figs. 3, 5, 6 and 7, so as to increase the heating surface of said members and thus cause a large quantity of air to be heated without liability of overheating part of the air, it being, of course, understood that the plate 20 is heated by the heat which radiates from the side wall plates of the member A. In view of the fact that the air-boxes are built up of wrought iron or steel plates and commercially rolled channels which are securely fastened together and the joints between same filled with cement or other packing, said boxes are inex pensive to manufacture, they will not warp when they are subjected to great heat, and they form efficient fire-fines and air conduits.

The fire gases that escape from the combustion chamber through the fire-ports 9 travel downwardly through the fire-flues 8 in the loop-shaped direction indicated by the arrows in Fig. 2 and escape through the smoke-ports 10 into the smoke-flue 4, and in view of the fact that the side walls of said fines are formed by the hollow air-heating members A said members A will be maintained at a high temperature. The cold air, or air to be heated, is supplied to the lower ends of the members A through the air intake ports 11 and circulates up through said members to the outlet ports 12in the counter-current direction indicated by the arrows in Fig. 4, the air absorbing the heat from the side wall plates of said members A and from the auxiliary heating plates 20 and thus becoming highly heated by the time it reaches the hot-air collecting chamber 14.

By constructing the furnace in the manner above described, namely, making the furnace proper separate and distinct from the air-heater, the air-heater will not be exposed to the fiame but only to the products of completed combustion. Consequently, the air-heater will not be over-heated or subjected to such an intense degree of heat that the metal members constituting same will warp or twist out of shape. The hollow members that constitute the air-heater have heating surfaces of sufficient area to cause the air to become highly heated before it enters the distributing ducts of the system, and in view of the fact that said members are spaced away from each other and are arranged at approximately right angles to the rear wall of the combustion chamber, they form fire-fines which extend in the direction or path that the products of combustion naturally take in leaving the combustion chamber and are accessible for cleaning through the fire-ports. By forming the inlet and outlet ports for the air and for the fire gases in such a manner that the air and fire gases circulate in opposite directions in approximately loop-shaped counter-currents, I not only increase the length of time that the air contacts with the surfaces from which it absorbs heat, but I also insure the coldest air passing along the coolest fire gases and the warmest air passing along the hottest fire gases, said counter-currents transmitting a maximum heat to the ingoing air.

A furnace of the construction above-do scribed can be manufactured at a low cost owing to the fact that the air-heating members are formed from flat metal plates of uniform shape and size and pieces of channel-iron or flanged or pressed members which can be bolted or riveted to the plates easily. Such a furnace can also be installed easily as the air-heater is separate and distinct from the furnace proper and is secured to same by tie-rods or in any other suitable manner. In addition to the desirable features above-mentioned there is no liability of the fire gases entering the ducts through which the air circulates because the front edges of the air boxes A are tightly closed by members separate and distinct from the transverse furnace wall 7 and the joints of said air-boxes are packed with cement or other suitable material that makes said boxes perfectly tight. Consequently, if the joints between the front edges of the members A and the wall 7 should open up the efficiency of the furnace would not be materially affected because the fire gases could not enter the ducts through which the air circulates.

As previously stated, my broad idea is not limited to a furnace of the construction shown in Figs. 1 to 6 in which the air-heating members are arranged at right angles to the rear wall of the combustion chamber and the cold-air supplying chamber and hot-air collecting chamber are arranged behind the heating members for these parts could be arranged in various other ways without departing from the spirit of my invention.

I prefer to make the air-heating members oblong-shaped and comparatively narrow but this is not essential as said members could be formed in various other ways. For example, in a round furnace, hollow boxes A of approximately V-shape in cross section could be arranged behind a circular combustion chamber 1, as shown in Figs. 8 and 9, and the cold-air supply chamber 13 could be made substantially crescent-shaped. The

air-collecting chamber 14L which receives the air that is heated in the members A could be arranged above said members, as shown in Fig. 8, instead of behind them, and the members A could be provided with substantially V-shaped vertically disposed auxiliary heating devices 20.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A hotair furnace comprising a furnace chamber, an air-heater consisting of a group of hollow members spaced away from each other so as to form alternately arranged airflues and fire-fines, an air-supply chamber having ports each of which communicates with one end of each of said air-fines, a hotair collecting chamber having ports which communicate with the-opposite ends of said air-flues, and means for causing the firegases from the furnace chamber to circulate through said fire-flues in an opposite direction to the circulation of the air through said air-fines, the air absorbing heat from the walls of the fiues through which it travels.

2. A hot-air furnace comprising a combustion chamber having a port wall, an air heater separate and distinct from said combustion chamber and arranged in sucha manner that the expansion and contraction of the combustion chamber will not affect the air heater and vice versa, the air heater comprising alternately arranged fire fines and air fines, an air supply chamber communicating with one end of said air fiues, a hot air collecting chamber communicating with the opposite end of said air fines, and means for causing the products of combustion to pass from the combustion chamber into the fire flues and travel through said fire flues in an opposite direction to the circulation of the air through said air fiues.

8. A hot-air furnace consisting of a furnace chamber and an air-heater which is separate and distinct from the furnace chamber and composed of alternately arranged vertically-disposed firc-fiues and air-fines of approximately oblong-shape in cross-section, the furnace chamber having a wall which entirely separates the air-heater from the furnace whereby expansion and contraction of the furnace chamber will not affect the air heater and vice versa, means whereby fiow of the fire-gases.

the fire-gases escaping from the furnace chamber can flow through ithe fire-flues of the air-heater in an opposite direction to the flow of the air through the air-fines of the air-heater, an air supply chamber communicating with one end of said air-fines, and a hot-air collecting chamber communieating with the opposite end of said air-fines.

4; A hot air furnace comprising a complete furnace consisting of a combustion chamber, fuel grate and ashpit, an air heater separate and distinct from the furnace and comprising a plurality of verti-, cally disposed hollow members of substantially oblong-shape in cross section arranged: to form a series of fire fiues that are located between a series of air fiues, ports in one wall of the furnace that establish communication between the combustion chamber and the upper ends of the air fines of the air heater, an air supply chamber communicat-iing with the lower ends of the air fines of the air heater, a hot air collecting chamber communicating with the upper ends of said air fines, and means for creating a clowndraft through the fire fiues so that the fire gases will travel through same in an opposite direction to the circulation of the air being heated.

5. A hot-air furnace comprising a group of substantially oblong-shaped hollow mem-, bers arranged vertically and spaced away from each other so as to form alternately ar ranged air-flues and fire-fines, a combustion chamber arranged on one side of said group of members and having ports which communicate with the upper ends of saidfirefines, a smoke-pipe communicating with the .lower ends of said 'fire-flues, and an air-supeply chamber and hot-air collecting chamber arranged on the other side of said group of members and in communication with the lower and upper ends, respeetively, of said air-fines whereby the air that is beingheated will travel in an opposite direction to the In testimony whereof I hereunto aflix my signature in the presence of two witnesses,

thisthirtieth day of December 1912.

JOHN ZELL'WEGER.

WVitnesses CORA M. BADGER, GE RGE BAKEWELL.

copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

